This invention relates to a novel compound having an antitumor activity, an antitumor agent comprising the compound as an active ingredient, and a method for treating tumors using the antitumor agent.
Many 5-fluorouracil type drugs (hereinafter abbreviated as 5-FU drugs) have been used as an antitumor agent that can be administered orally, but their mechanism of action is quite the same, and also the effects obtained are not deemed sufficient. Besides, tumors resistant to 5-FU drugs have come out. It has therefore been demanded to develop a new antitumor agent having a different mechanism of action from that of 5-FU drugs which is more efficacious than 5-FU drugs and is effective on 5-FU-resistant tumors as well.
An object of the present invention is to provide a potent antitumor agent which has a novel chemical structure not heretofore reported and exhibits efficacy on 5-FU-resistant tumors as well.
As a result of extensive study, the inventors of the present invention have found that novel pyrazole derivatives represented by formula (I) hereinafter shown exhibit a powerful antitumor activity even on 5-FU-resistant tumors. It has also been found that the pyrazole derivatives are also effective on P glycoprotein-expressed multiple drug-resistant strains that have been a clinical problem.
The present invention provides a compound represented by formula (I) or a salt thereof; 
wherein R1 and R2, which may be the same or different, each represent a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an amino group, an alkylamino group, an aryl group or an alkyl group, in which the alkyl group may be substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group; R3 and R4, which may be the same or different, each represent a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkylamino group, an aryl group or an alkyl group, in which the alkyl group may be substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group; R5 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or an arylalkyl group, in which the alkyl group may be substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group; Q represents an amidino group, a cycloalkyl group, a phenyl group or a monocyclic heterocyclic group except a pyrimidinyl group bonded to the N atom at its 2-position, and the cycloalkyl, phenyl or monocyclic heterocyclic group may have one or more substituents selected from the group consisting of an alkyl group, an alkyl group substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group, a halogen atom, a hydroxy group, an alkoxy group, an alkoxyalkoxy group, an amino group, an alkylamino group, an acylamino group, an alkylaminoalkylamino group, a nitro group, a cyano group, a carbamoyl group, a thiol group, an alkylthio group, an arylthio group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, an aminosulfonyl group, an alkylaminosulfonyl group, an arylaminosulfonyl group, and an aryl group; G represents a nitrogen-containing saturated heterocyclic structure represented by formula: 
wherein X1 represents a nitrogen atom or CH,
in which structure the ring may have a keto group and may have one or more substituents selected from the group consisting of an alkyl group, analkyl group substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group, a halogen atom, a hydroxy group, an alkoxy group, an amino group, an alkylamino group, and an aryl group; Z represents a phenyl group, a heterocyclic group or a phenyl or heterocyclic group having one or more substituents selected from the group consisting of an alkyl group, an alkyl group substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group, a halogen atom, a hydroxy group, an alkoxy group, a thiol group, an alkylthio group, an amino group, an alkylamino group, an acylamino group, a nitro group, a cyano group, a carbamoyl group, and an aryl group, in which two substituents on the phenyl or heterocyclic group may be connected to each other to form a ring to provide a condensed bicyclic structure as a whole; the substituent on Z and the substituent on G may be connected to each other to form a condensed tricyclic or tetracyclic structure as a whole.
The compound represented by formula (I) includes both cis- and trans-forms attributed to the double bond of the alkenyl moiety.
Terminologies and expressions used in the present invention are explained. The terminology xe2x80x9ccis-formxe2x80x9d means a configuration having R3 and R4 on the same side of the double bond, and the terminology xe2x80x9ctrans-formxe2x80x9d denotes a configuration in which R3 and R4 are on the opposite sides of the double bond.
The terminologies xe2x80x9calkyl groupxe2x80x9d, xe2x80x9calkenyl groupxe2x80x9d and xe2x80x9calkynyl groupxe2x80x9d are intended to include straight-chain groups and branched groups and preferably indicate those having 1 to 6 (2 to 6 as to alkenyl and alkynyl groups) carbon atoms.
The xe2x80x9calkoxy groupxe2x80x9d preferably include those having 1 to 6 carbon atoms.
The term xe2x80x9caryl groupxe2x80x9d means a monovalent group derived from an aromatic hydrocarbon by removing one hydrogen atom from its nucleus and includes, for example, phenyl, tolyl, biphenyl and naphthyl groups.
In the xe2x80x9caminoalkyl groupxe2x80x9d as referred to herein, the amino moiety may be bonded to any position of the alkyl moiety, and the alkyl moiety preferably contains 1 to 6 carbon atoms.
The terminology xe2x80x9calkylamino groupxe2x80x9d is indented to include an amino group substituted with one alkyl group and an amino group substituted with two alkyl groups, which maybe the same or different, in which the alkyl group preferably contains 1 to 6 carbon atoms.
The term xe2x80x9cacyl groupxe2x80x9d means a carbonyl group (xe2x80x94COxe2x80x94) with a hydrogen atom, an alkyl group or an aryl group bonded thereto, including formyl, acetyl, propanoyl and benzoyl groups. The alkyl group bonded to the carbonyl group preferably contains 1 to 6 carbon atoms, and the aryl group bonded is preferably a phenyl group.
The term xe2x80x9cheterocyclic groupxe2x80x9d designates a group derived from a monocyclic or bicyclic, saturated or unsaturated heterocyclic compound containing in its ring one or more hetero atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom, the position of the hetero atom(s) being not limited. Monocyclic heterocyclic groups include those derived from monocyclic heterocyclic compounds, such as pyrrole, furan, thiophene, pyrrolidine, tetrahydrofuran, tetrahydrothiophene, imidazole, pyrazole, imidazolidine, pyrazolidine, oxazole, thiazole, oxadiazole, thiadiazole, pyridine, dihydropyridine, tetrahydropyran, piperidine, pyridazine, pyrimidine, triazine, pyrazine, piperazine, dioxane, pyran, and morpholine. Bicyclic heterocyclic groups include those derived from bicyclic heterocyclic compounds, such as benzofuran, indolizine, benzothiophene, indole, naphthyridine, quinoxaline, quinazoline, and chroman.
The terminology xe2x80x9cnitrogen-containing saturated heterocyclic groupxe2x80x9d means a group derived from a saturated heterocyclic compound which contains in its ring one nitrogen atom and may further contain one or more hetero atoms selected from a nitrogen atom, an oxygen atom and a sulfur atom. Examples are those derived from such compounds as pyrrolidine, imidazolidine, pyrazolidine, piperidine, piperazine, and homopiperazine.
The expression xe2x80x9ctwo substituents on the phenyl or heterocyclic group may be connected to each other to form a ring to provide a condensed bicyclic structure as a wholexe2x80x9d as used in the definition of Z is intended to mean that two substituents on Z are bonded together to form a structure represented by formula: 
wherein X2 and X3 each independently represent an oxygen atom, a sulfur atom, NH or CH2; and 1 represents an integer of 1 to 3, so that Z has a condensed bicyclic structure as a whole. For example, where Z is a phenyl group, the condensed bicyclic structure has the following structure: 
The expression xe2x80x9cthe substituent on Z and the substituent on G may be connected to each other to form a condensed tricyclic or tetracyclic structure as a wholexe2x80x9d as used in the definition of G and Z is intended to mean that the substituent on Z and the substituent on G may be connected to each other to form a cyclic structure represented by formula: 
wherein X4 represents an oxygen atom, a sulfur atom, NH or CH2; and m and n each represent 0 or an integer of 1 to 3, so that G and Z form a condensed tricyclic or tetracyclic structure as a whole. For example, where G is a piperazinyl group, and Z is a phenyl group, there is formed the following structure as a whole: 
In formula (I),
R1 preferably represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an amino group, a phenyl group or an alkyl group, in which the alkyl group may be substituted with an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
R2 preferably represents a hydroxy group, an alkoxy group, an amino group or an alkyl group, in which the alkyl group may be substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
R3 preferably represents a hydrogen atom or an alkyl group, in which the alkyl group may be substituted with an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
R4 preferably represents a hydrogen atom or an alkyl group, in which the alkyl group may be substituted with an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
R5 preferably represents a hydrogen atom or an alkyl group, in which the alkyl group may be substituted with an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
Q preferably represents a phenyl group or a monocyclic heterocyclic group. The phenyl group or monocyclic heterocyclic group may have a substituent. The monocyclic heterocyclic group is preferably unsaturated and still preferably a 5- or 6-membered ring.
Q still preferably represents a 5- or 6-membered, unsaturated, monocyclic heterocyclic group, exclusive of a pyrimidinyl group bonded at the 2-position thereof, containing at least one nitrogen atom in its ring, such as one derived from pyridine, pyrimidine or pyridazine.
Substituents on Q preferably include a halogen atom, a cyano group, a hydroxy group, an alkoxy group, an alkylthio group, an alkylsulfinyl group, an alkylsulfonyl group, and an alkyl group.
G preferably represents a 5- or 6-membered nitrogen-containing saturated heterocyclic structure represented by formula: 
wherein X1 represents a nitrogen atom or CH, particularly one derived from piperazine or piperidine.
The heterocyclic group as Z is preferably a 5- or 6-membered monocyclic heterocyclic group, particularly an unsaturated one. Examples of the preferred heterocyclic group are pyridyl, pyridazyl, pyrazyl, pyrimidinyl and triazyl groups.
Z preferably represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted pyrimidinyl group.
When substituted, Z preferably has one or two substituents selected from the group consisting of a halogen atom, a hydroxy group, a cyano group, an alkyl group, and an alkyl group substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
Z also preferably represents a condensed bicyclic structure formed by connecting two substituents on the phenyl or heterocyclic group to form a ring represented by formula: 
wherein X2 and X3 each independently represent an oxygen atom, a sulfur atom, NH or CH2; and 1 represents an integer of 1 to 3,
Z still preferably represents a phenyl group having two substituents, either the same or different, selected from the group consisting of a halogen atom, a hydroxy group, a cyano group, an alkyl group, and an alkyl group substituted with a halogen atom, an amino group, an alkylamino group, a hydroxy group, an alkoxy group, a thiol group or an alkylthio group.
Of the geometrical isomers of the compounds represented by formula (I), the trans-form (in which R3 and R4 are on the opposite sides of the double bond) is preferred.
The compound represented by formula (I) can be prepared through various routes. A typical process is shown below.
Process A: 
wherein R1, R2, R4, Q, G, and Z are as defined above.
That is, compound (II) and a basic compound Hxe2x80x94Gxe2x80x94Z are subjected to Mannich reaction to obtain compound (III), which is then reduced to compound (IV), followed by dehydration to give compound (I).
Each reaction involved will be explained in detail.
Mannich Reaction
Compound (II) and a basic compound Hxe2x80x94Gxe2x80x94Z are reacted in a solvent in the presence of a condensing agent to obtain compound (III). It is preferred for the compound Hxe2x80x94Gxe2x80x94Z to be used in the salt form such as a hydrochloride, a hydrobromide.
Suitable condensing agents include paraformaldehyde and formaldehyde.
Suitable solvents include alcohols, such as methanol, ethanol and propanol; amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; halogenated hydrocarbons, such as chloroform, dichloromethane, and carbon tetrachloride; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons, such as benzene, toluene, and xylene; and mixtures thereof.
The reaction is carried out usually at xe2x88x9220xc2x0 to 150xc2x0 C., preferably 0xc2x0 to 100xc2x0 C., for 5 minutes to 120 hours, preferably 30 minutes to 72 hours.
Reduction
Reduction of compound (III) yields compound (IV) The reduction can be conducted by a method custamrily used in the art. For example, compound (III) is treated with a reducing agent or hydrogenated in the presence of a catalyst.
Suitable reducing agents include boron hydride compounds and aluminum hydride compounds, such as sodium borohydride, sodium cyanoborohydride, and lithium aluminum hydride. Useful catalysts include palladium, Raney nickel, and platinum oxide.
An appropriate solvent is chosen according to the reducing agent. Useful solvents include alcohols, such as methanol, ethanol, and propanol; amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; halogenated hydrocarbons, such as chloroform, dichloromethane, and carbon tetrachloride; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons, such as benzene, toluene, and xylene; and mixtures thereof.
The reaction is carried out usually at xe2x88x9220xc2x0 to 150xc2x0 C., preferably 0xc2x0 to 100xc2x0 C., for 5 minutes to 72 hours, preferably 10 minutes to 24 hours.
Dehydration
Dehydration of compound (IV) affords compound (I). The dehydration can be performed in a method commonly used in the art. For example, compound (IV) is heated in the presence of an acid.
Either organic acids or inorganic acids can be used for dehydration. Examples of useful inorganic acids are hydrochloric acid, sulfuric acid, hydrobromic acid, and potassium hydrogensulfate. Examples of useful organic acids are p-toluenesulfonic acid, methanesulfonic acid, and oxalic acid. Inorganic acids are preferred to organic ones. In addition, alumina is also useful.
A solvent may be used for dehydration. Suitable solvents include amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; halogenated hydrocarbons, such as chloroform, dichloromethane, and carbon tetrachloride; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons, such as benzene, toluene, and xylene; and mixtures thereof.
The reaction is conducted usually at xe2x88x9220xc2x0 to 150xc2x0 C., preferably 0xc2x0 to 100xc2x0 C., for 5 minutes to 72 hours, preferably 10 minutes to 24 hours.
Process A described above provides compound (I) in which R3 is a hydrogen atom, and the alkenyl group moiety is trans. Compound (I) in which R3 is an alkyl group and/or the alkenyl group moiety is cis can be synthesized according to process B shown below.
Process B 
wherein A represents a chlorine atom, a bromine atom or an iodine atom; and R1, R2, R3, R4, R5, Q, G, and Z are as defined above.
That is, compound (I) can be obtained by subjecting compound (IIa) and compound (V) to Wittig reaction. More specifically, compound (V) and a tertiary phosphine compound are reacted in a solvent. The resulting phosphonium salt is treated with a base in a solvent, and compound (IIa) is added thereto to obtain compound (I).
Suitable tertiary phosphine compounds include triphenylphosphine and tri-n-butylphosphine.
Suitable bases include n-butyllithium, phenyllithium, sodium hydride, potassium t-butoxide, sodium ethoxide, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
Useful solvents includes ethers, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons, such as benzene, toluene, and xylene; alcohols, such as methanol, ethanol, and propanol; amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; halogenated hydrocarbons, such as chloroform, dichloromethane, and carbon tetrachloride; and mixtures thereof.
The reaction is carried out usually at 300 to 150xc2x0 C., preferably 50xc2x0 to 100xc2x0 C., for a period of 5 minutes to 72 hours, preferably 10 minutes to 24 hours.
The starting compounds (II) and (IIa), the basic compound Hxe2x80x94Gxe2x80x94Z, and compound (V) are known compounds or can easily be synthesized in a known manner.
Compound (I) of the present invention can also be prepared through the following process C (reductive amination or substition via allylation).
Process C 
wherein M represents a metal (e.g., an alkali metal, an alkaline earth metal, tin, zinc, nickel, etc.); and R1, R2, R3, R5, Q, G, and Z are as defined above.
Compound (IIa) is reacted with an appropriate allyl metal compound, or allylsilane is added to compound (IIa) in the presence of a Lewis acid, to form compound (VI). The hydroxy group of compound (VI) is protected to obtain compound (VII), which is oxidized to convert to compound (VIII). Compound (VIII) and a basic compound, such as substituted piperazine, are subjected to reductive amination to obtain compound (X). If necessary, the protective group is removed from compound (X). Compound (X) is dehydrated to give compound (I) in which R4 is a hydrogen atom. Compound (X) can also be obtained by reducing compound (VIII) or reacting compound (VIII) with an alkyl metal compound to obtain compound (IX), converting the hydroxy group to a releasable group, followed by substitution reaction with a basic compound, such as substituted piperazine.
Each reaction involved in process C will be described in detail.
Addition Reaction
Compound (IIa) is reacted with an appropriate allyl metal compound, or allylsilane is added to compound (IIa) in the presence of a Lewis acid (e.g., titanium tetrachloride), to form compound (VI).
The allyl metal compound to be used includes allyl lithium, an allyl magnesium halide, and an allyltin compound. The allylsilane compound to be used includes an allyltrialkylsilane and an allyltriarylsilane. Suitable Lewis acids include titanium tetrachloride.
Solvents that can be used in the addition reaction include ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane, pentane, benzene, toluene, and xylene; and mixtures thereof. Where an allyltin compound is used, water or a water-containing ether solvent is also useful.
The addition reaction is carried out usually at xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9278xc2x0 to 70xc2x0 C., for a period of 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Protection of Hydroxy Group
The hydroxy group of compound (VI) can be protected with a protective group generally used in the art. Examples of such a protective group include substituted methyl ether groups, such as a methoxymethyl ether group, a methylthiomethyl ether group, and a benzyloxymethyl ether group; substituted ethyl ether groups, such as a 1-methoxyethyl ether group and a 2,2,2-trichloroethyl ether group; a benzyl ether group; substituted benzyl ether groups, such as a p-methoxybenzyl ether group; silyl ether groups, such as a triethylsilyl group and a t-butyldimethylsilyl group; ester groups, such as an acetyl group; and carbonate groups, such as a methoxycarbonyl group and a 2,2,2-trichloroethoxycarbonyl group.
Oxidation
Compound (VIII) can be obtained from compound (VII) in a manner usually adopted in the field of the art. For example, compound (VII) is subjected to stoichiometric oxidation reaction with an oxidizing agent (e.g., osmium tetroxide) or catalytic oxidation reaction with a co-oxidizing agent to once obtain a diol compound, which is then subjected to ordinary oxidation reaction, such as decomposition with periodic acid, to give compound (VIII). Alternatively, compound (VIII) can be obtained by subjecting compound (VII) to ordinary ozone decomposition accompanying a reductive treatment in a solvent.
Oxidizing agents useful for the formation of a diol compound include potassium permanganate and osmium tetroxide. Co-oxidizing agents useful for the same purpose include hydrogen peroxide, a hydrogen peroxide aqueous solution, perchloric acid, perchloric acid salts (e.g., sodiumperchlorate), N-methylmorpholine-N-oxide, and potassium hexacyanoferrate (III).
Suitable solvents for use in the formation of a diol compound include alcohols, such as methanol, ethanol, and t-butanol; ketones, such as acetone and methyl ethyl ketone; chlorine-containing solvents, such as dichloromethane and dichloroethane; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane, pentane, and benzene; water; and mixtures thereof.
The reaction for the formation of a diol compound is conducted usually at xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9278xc2x0 C. to room temperature, for a period of from 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Decomposition of the diol with periodic acid is performed in a solvent by using periodic acid, a periodic acid salt, etc. as an oxidizing agent. Suitable solvents include alcohols, such as methanol, ethanol, and t-butanol; ketones, such as acetone and methyl ethyl ketone; chlorine-containing solvents, such as dichloromethane and dichloroethane; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane, pentane, and benzene; water; and mixtures thereof.
The reaction is conducted usually at xe2x88x9220xc2x0 to 100xc2x0 C., preferably 0xc2x0 C. to room temperature, for 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Solvents that can be used in ozone decomposition include alcohols, such as methanol, ethanol, and propanol; ketones, such as acetone and methyl ethyl ketone; chlorine-containing solvents, such as dichloromethane and dichloroethane; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane and pentane; and mixtures thereof.
The ozone decomposition reaction is effected usually at xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9278xc2x0 C. to room temperature, for 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Reductive Amination
The reaction for obtaining compound (X) from compound (VIII) is conducted in a conventional manner. For example, compound (VIII) is reacted with a basic compound, such as substituted piperazine, and the product is treated with a reducing agent to yield compound (X).
Useful reducing agents include complex hydrides, such as lithium aluminum hydride, sodium borohydride, and sodium cyanoborohydride, and diboran. Hydrogenation in the presence of a catalyst, such as Raney nickel or palladium-on-carbon, will do.
Solvents to be used include alcohols, such as methanol, ethanol, and propanol; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane, pentane, benzene, toluene, and xylene; and mixtures thereof.
The reductive amination reaction is carried out usually at a temperature of xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9210xc2x0 C. to room temperature, for a period of from 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Reduction
Compound (IX) in which R5 is a hydrogen atom can be obtained by reducing the carbonyl group of compound (VIII). The reduction can be carried out in a conventional manner, for example, by treatment with a reducing agent or hydrogenation in the presence of a catalyst. Useful reducing agents include boron hydride compounds and aluminum hydride compounds, such as sodium borohydride and lithium aluminum hydride. Useful catalysts include palladium, Raney nickel, and platinum oxide.
The reaction can be conducted in a solvent, which is to be chosen according to the kind of the reducing agent. Useful solvents include alcohols, such as methanol, ethanol, and propanol; amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; chlorine-containing solvents, such as chloroform, dichloromethane, and carbon tetrachloride; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; hydrocarbons, such as hexane, pentane, benzene, toluene, and xylene; and mixture thereof.
The reaction temperature usually ranges from xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9278xc2x0 to room temperature. The reaction period usually ranges from 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Addition of Alkyl Group
Where R5 is not a hydrogen atom, a corresponding compound (IX) can be obtained by reacting compound (VIII) with an alkyl metal compound.
The alkyl addition reaction can be conducted in a customarily employed manner. For example, compound (VIII) is treated with an alkyllithium or an alkylmagnesium halide.
Suitable alkyl metal compounds include alkyllithiums, such as methyllithium and ethyllithium, and alkylmagnesiumhalides, such as methylmagnesium iodide and ethylmagnesium bromide.
The reaction can be performed in the presence of a solvent, such as an ether solvent, e.g., diethyl ether, tetrahydrofuran or dioxane, a hydrocarbon solvent, e.g., hexane, pentane, benzene, toluene or xylene, or a mixture thereof.
The reaction is executed usually at a temperature of xe2x88x9278xc2x0 to 100xc2x0 C., preferably xe2x88x9278xc2x0 C. to room temperature, for a period of 5 minutes to 120 hours, preferably 30 minutes to 48 hours.
Substitution with Amino Group
The hydroxy group of compound (IX) is once changed to a releasable group, such as a halogen atom or a sulfonic ester group, and then the resulting derivative of compound (IX) is reacted with a basic compound, such as substituted piperazine, to obtain compound (X).
Conversion of a hydroxy group to a releasable group, such as a halogen atom or a sulfonic ester group, can be effected in a usual manner. For example, halogenation is achieved by treating with a phosphorus trihalide, a phosphorus pentahalide, etc. in a solvent, e.g., dichloromethane or chloroform; or treating with a Vilsmeier reagent, such as N,N-dimethylchloroforminium chloride or bromide, in a solvent, such as N,N-dimethylformamide or dioxane. Sulfonylation can be conducted by, for example, treating with methanesulfonyl chloride, p-toluenesulfonyl chloride, etc. in a solvent in the presence of an appropriate base.
The substitution reaction between the resulting derivative of compound (IX) and a basic compound (e.g., substituted piperazine) can be performed in a conventional manner. For example, a mixture of the derivative of compound (IX) and a basic compound (e.g., substituted piperazine) is heated in a solvent (e.g., acetonitrile) in the presence of a base (e.g., potassium carbonate) to give compound (X).
Removal of Protective Group
The hydroxy-protective group of compound (X) can be removed under conditions known for the protective group used.
Dehydration
Dehydration of compound (XI) gives compound (I). The dehydration can be conducted in a known manner, for example, by heating in the presence of an acid.
Either organic acids or inorganic acids can be used. Examples of useful inorganic acids are hydrochloric acid, sulfuric acid, hydrobromic acid, and potassium hydrogensulfate. Examples of useful organic acids are p-toluenesul fonic acid, methanesul fonic acid, and oxalic acid. Inorganic acids are preferred to organic ones. In addition, alumina is also useful.
A solvent maybe used in the dehydration. Suitable solvents include amide solvents, such as N,N-dimethylformamide, acetamide, and dimethylacetamide; halogenated hydrocarbons, such as chloroform, dichloromethane, and carbon tetrachloride; ethers, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons, such as benzene, toluene, and xylene; and mixtures thereof.
The reaction is conducted usually at xe2x88x9220xc2x0 to 150xc2x0 C., preferably 0xc2x0 to 100xc2x0 C., for 5 minutes to 72 hours, preferably 10 minutes to 24 hours.
Compound (I) in which the alkenyl group moiety is trans can be synthesized according to process D shown below.
Process D 
wherein R1, R2, R3R4R5, Q, Z, and Z are as defined above; R6 represents a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, a chlorine atom, a bromine atom or an iodine atom; and R7 represents an alkoxycarbonyl group, a carbamoyl group or a cyano group.
That is, compound (IIa) and compound (XIII) are condensed to obtain compound (XII). Compound (XII) and a basic compound Hxe2x80x94Gxe2x80x94Z are reacted (reductive aminated) to give compound (I). Compound (XII) where R5 is a hydrogen atom is also obtainable by condensing compound (IIa) and compound (XIV) to obtain compound (XV) and reducing compound (XV).
Each reaction included in process D will be described below in detail.
Condensation
The condensation reaction of compound (IIa) into compound (XII) or (XV) can be carried out by the condensation generally employed in the art. For example, compound (IIa) and compound (XIII) or (XIV) are subjected to Aldol condensation; or compound (IIa) and a phosphonium salt synthesized from compound (XIII) or (XIV) are subjected to Wittig reaction; or compound (IIa) and an alkylphosphorous diester synthesized from compound (XIII) or (XIV) to Wittig-Horner reaction. Phosphonium salts synthesized from compound (XIII) or (XIV) include a triphenylphosphonium salt and a tri-n-butylphosphonium salt. Alkylphosphorous diesters synthesized from compound (XIII) or (XIV) include dimethyl alkylphosphites, diethyl alkylphosphites, and diphenyl alkylphosphites.
Reduction
Compound (XII) in which R5 is a hydrogen atom can be obtained by treating compound (XV) in a solvent in the presence of a reducing agent. Where the reduction proceeds to give a corresponding alcohol, the resulting alcohol is oxidized to obtain compound (XII).
Suitable reducing agents include those generally used for 1,2-reduction of an xcex1,xcex2-unsaturated carbonyl compound, such as diisobutylaluminum hydride or lithium aluminum hydride.
Reductive Amination
Reductive amination can be conducted in the same manner as described above.
If desired, the compounds according to the present invention can be converted to their physiologically acceptable salts with inorganic acids, such as hydrochloric acid, sulfuric acid, and phosphoric acid, or organic acids, such as formic acid, acetic acid, and methanesulfonic acid. Further, the compounds or the salts of the present invention can exist in the form of a hydrate.
The antitumor effect of the compounds according to the present invention will be demonstrated in the following Test Example.
Tumor cells PC-12 and PC-6, which had been serially cultured in RPMI 1640 containing 10% fetal bovine serum, 2 mM L-glutamine, and 100 xcexcg/ml of kanamycin sulfate, were inoculated to a 96-well microplate (1.0xc3x97103 cells-PC-12/150 xcexcl/well; 5.0xc3x97103 cells-PC-6/150 xcexcl/well). After 24-hour incuvation, 50 xcexcl of a preparation containing each of the compounds of Examples 5 to 8 and Example 13 (hereinafter described) in a varied concentration was added to each well, followed by culturing for 3 days. A 5 mg/ml solution of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) was added in an amount of 20 xcexcl per well. Four hours later, the culture broth was removed, 150 xcexcl/well of dimethyl sulfoxide was added to the residue, and the absorbance was measured at 540 nm. The concentration of the compound which showed 50% inhibition on cell growth as compared with a control group (GI50; ng/ml) is shown as an antitumor effect in Table 1 below.
As is apparent from Table 1, the compounds according to the present invention exhibit an antitumor activity and is applicable as an antitumor agent in the treatment of various tumors.
The antitumor agent according to the present invention can be administered through various routes, such as intravenous injection, intramuscular injection, subcutaneous injection, or oral administration. Intravenous administration of injectable aqueous preparations and oral administration are preferred. Aqueous preparations can be prepared by converting the compound of the invention into an acid addition salt with a pharmacologically acceptable acid. For oral administration, the compound can be used either in a free form or in a salt form.
The compounds of this invention and the salts thereof can be formulated into various pharmaceutical compositions in a manner commonly employed in the art. Suitable dosage forms can be selected according to the administration route. Typical dosage forms for oral administration include tablets, powders, granules, capsules, solutions, syrups, elixirs, and oily or aqueous suspensions.
Injectable solutions can contain stabilizers, preservatives, and dissolving aids. The solution which may contain these adjuvants can be put in a container and made into a solid preparation by, for example, freeze-drying, which can be dissolved on use. A single injection dose may be put in an ampule, or multiple doses may be put in a container.
Liquid preparations include solutions, suspensions, emulsions, etc. In formulating the pharmaceutical composition into these liquid preparations, suspending agents, emulsifying agents, and the like can be used as additives.
The dosage of the antitumor agent containing the compound of the present invention as an active ingredient is 10 mg to 3 g, preferably 50 mg to 2 g, in a single dose/day for an adult. Administration is preferably repeated at appropriate intervals.